Constellations

       Constellations

       In the past, people looked up at the night sky and "connected the dots" formed by the stars. They saw patterns that reminded them of bears, dogs, a swan, a lion, and even a sea monster! Today, scientists divide the night sky into 88 constellations. A constellation is a group of stars that forms a pattern. A map of constellations looks much like a map of the United States with all the states in the country outlined. Some are rectangles, others have odd shapes. Many of the constellation names are the names of the star patterns people used long ago.

       Dividing the sky into sections makes studying stars easier. A constellation is a little bit like a star's address. For example, if you tell someone which state you live in, it lets that person know which part of the country you live in. Knowing which constellation a star is in lets you know which part of the sky to look at to find that star.

       Two stars that look close together in the same constellation are not necessarily very close in reality. One star may be billions of kilometers farther from Earth than the other. They appear to be close together because they are in the same direction from Earth.

       People who live in different parts of the world see different sections of the sky and different constellations. The Earth can be divided into two halves along the equator. The half to the north of the equator is called the Northern Hemisphere. The half to the south is called the Southern Hemisphere. The United States is in the Northern Hemisphere. Ursa Major can be seen in the Northern Hemisphere. But it is not visible to people in the Southern Hemisphere.